The Effects of Third Substances at the Particle/Surface Interface in Compressor Fouling

2017 ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Devid Dainese ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Environmental Conditions ◽  
Particle Surface ◽  
Particle Diameter ◽  
Surfactant Solution ◽  
Solid Particles ◽  
Normal Velocity ◽  
Plant Design ◽  
Inorganic Matter ◽  
Starting Point

Since the beginning of the 1950s, manufacturers and operators have struggled to understand, reduce and eliminate compressor fouling and its effects on gas turbine operation. Several devices (inertial separators, barriers, filters, etc.) and strategies (on-line and off-line washing, manual cleaning, etc.) have been adopted in order to limit and/or eliminate the foulants which stick to the compressor blade and vane surfaces. The state of the power plant design and installation and environmental conditions determine the rate of fouling and, in turn, gas turbine performance losses. The types of contaminant (organic or inorganic), their concentration and their ability to stick are variable depending on the weather conditions. Desert, tropical, rural, and off-shore conditions are characterized by different foulants with different characteristics which determine compressor fouling. In this paper, an analysis of the influence of third substances at the particle/surface interface is presented. The analysis is carried out on two different compressor rotors, transonic and subsonic. Firstly, a sensitivity analysis is proposed related to the particle diameter and foulant mixture in order to highlight the influence of air humidity due to environmental conditions or the pressure drop after the filtration stages. The effects of a water electrolytic solution (generated by the presence of inorganic matter) and a water surfactant solution (used in the case of washing) are also considered. In this case, the properties of the mixture substance (solid particles bound by a liquid film) are considered. Secondly, using previous numerical analyses (particle-laden flow with a Eulerian-Lagrangian approach) as a starting point, the variation in particle sticking ability is evaluated against the presence of third substances (water solutions and oily substances) and the particle kinematic characteristics using a sticking model based on an energy balance equation. The results show the influence of the third substance on particle sticking capability using a susceptibility-to-fouling criterion. Particularly in the presence of humid conditions, sticking capability increases with respect to dry conditions, even though the major effects are due to the mixture viscosity and not only to the presence of liquid water. The sticking capability of the mixture varies according to particle diameter as a function of the particle normal velocity. The results are presented in order to easily quantify the effects of the presence of a third substance at the particle/surface interface according to the type of liquid phase involved in the sticking process.

Externally-Fired Combined Cycle Repowering of Existing Steam Plants

1993 ◽  
Author(s):  
Christian L. Vandervort ◽  
Mohammed R. Bary ◽  
Larry E. Stoddard ◽  
Steven T. Higgins
Keyword(s):  
Heat Exchanger ◽  
Steam Turbine ◽  
Gas Turbine ◽  
High Efficiency ◽  
Low Cost ◽  
Operating Experience ◽  
Capital Cost ◽  
Combined Cycle ◽  
Plant Design ◽  
Generating Capacity

The Externally-Fired Combined Cycle (EFCC) is an attractive emerging technology for powering high efficiency combined gas and steam turbine cycles with coal or other ash bearing fuels. The key near-term market for the EFCC is likely to be repowering of existing coal fueled power generation units. Repowering with an EFCC system offers utilities the ability to improve efficiency of existing plants by 25 to 60 percent, while doubling generating capacity. Repowering can be accomplished at a capital cost half that of a new facility of similar capacity. Furthermore, the EFCC concept does not require complex chemical processes, and is therefore very compatible with existing utility operating experience. In the EFCC, the heat input to the gas turbine is supplied indirectly through a ceramic heat exchanger. The heat exchanger, coupled with an atmospheric coal combustor and auxiliary components, replaces the conventional gas turbine combustor. Addition of a steam bottoming plant and exhaust cleanup system completes the combined cycle. A conceptual design has been developed for EFCC repowering of an existing reference plant which operates with a 48 MW steam turbine at a net plant efficiency of 25 percent. The repowered plant design uses a General Electric LM6000 gas turbine package in the EFCC power island. Topping the existing steam plant with the coal fueled EFCC improves efficiency to nearly 40 percent. The capital cost of this upgrade is 1,090/kW. When combined with the high efficiency, the low cost of coal, and low operation and maintenance costs, the resulting cost of electricity is competitive for base load generation.

scholarly journals The Dynamics of Suspended Solid Particles in a Two Stage Gas Turbine

1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Suspended Solid ◽  
Solid Particles ◽  
Two Stage ◽  
Particle Momentum ◽  
Performance Deterioration ◽  
And Performance

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three dimensional particle trajectories in a two stage turbine. The solution takes into account the influence of the variation in the three dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental Laser Doppler Velocimetry (LDV) measurements. The results show the three dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distribution in the flow field are determined by particle-blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.

Effect of the Environmental Conditions of Tropical Climates on the Performance Parameters of a Gas Turbine Power Generation Plant

2020 ◽  
Author(s):  
J. Fajardo ◽  
D. Barreto ◽  
T. Castro ◽  
I. Baldiris
Keyword(s):  
Power Plant ◽  
Relative Humidity ◽  
Gas Turbine ◽  
Output Power ◽  
High Temperatures ◽  
Environmental Conditions ◽  
Thermal Efficiency ◽  
Specific Work ◽  
Atmospheric Conditions ◽  
Compressor Inlet

Abstract It is known that high temperatures adversely affect the performance of gas turbines, but the effect of the combination of atmospheric conditions (temperature and relative humidity -RH-) on the operation of this type of system is unknown. In this work the effects of atmospheric conditions on the energy and exergy indicators of a power plant with gas turbine were studied. The indicators studied were the mass flow, the specific work consumed by the compressor, specific work produced by the turbine, the combustion gas temperature, the NO concentration, the net output power, the thermal efficiency, the heat rate, the specific consumption of fuel, the destruction of exergy and exergy efficiency. Among the results, it is noted that for each degree celsius that reduces the temperature of the air at the compressor inlet at constant relative humidity on average, the mass flow of dry air increases by 0.27 kg/s, the specific work consumed by the compressors decreases by 0.45%, the output power increases by 1.17% and the thermal efficiency increases by 0.8%, the exergy destruction increases by 0.72% and the exergy efficiency increases by 0.81%. In addition, humidity changes relative to high temperatures are detected more significantly than at low temperatures. The power plant studied is installed in Cartagena, Colombia and since it is not operating in the design environmental conditions (15 °C and 60% relative humidity) it experiences a loss of output power of 6140 kW and a drop in thermal efficiency of 5.12 %. These results allow considering the implementation of air cooling technologies at the compressor inlet to compensate for the loss of power at atmospheric air conditions.

Experimental Investigation of Convective Melting of Granular Packed Bed Under Microgravity

2000 ◽  
Author(s):  
J. Jiang ◽  
Y. Hao ◽  
Y.-X. Tao
Keyword(s):  
Experimental Investigation ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Vertical Direction ◽  
Packed Bed ◽  
Melting Rate ◽  
Control Flow ◽  
Solid Particles ◽  
Average Particle ◽  
Ice Particles

Abstract To improve the understanding of convective melting of packed solid particles in a fluid, an experimental investigation is conducted to study the melting characteristics of a packed bed by unmasking the buoyancy forces due to the density difference between the melt and solid particles. A close-loop apparatus, named the particle-melting-in-flow (PMF) module, is designed to allow a steady state liquid flow under a specified temperature. The module is on board NASA’s KC-135 reduced gravity aircraft for the experiments. In the test module, water is used as the fluid, and ice particles are fed to the test section at the beginning of the test. As the liquid flows though the bed, the solid grains melt. A perforate plate, through which liquid can flow while the ice particles are retained, bounds the downstream of the packed bed. From the digital video images the local packed bed thickness is measured under control flow rate, and the melting rate is determined. The temperature distribution along the horizontal direction and vertical direction is measured using 19 thermocouples. An infrared camera is mounted to record the local temperature variation between liquid and solid. The melting rates are presented as a function of upstream flow velocity, temperature and initial average particle size of the packed bed. It is found that the melting rate is influenced mainly by the ratio of the Reynolds number (Re, based on the initial particle diameter) to the square of the Froud number (Fr), and me Stefan number (Ste). In general, the dimensionless melting rate decreases as Re/Fr2 increases and increases as Ste increases. With the absence of gravity, i.e., Froud number approaches infinity, a maximum melting rate can be achieved for otherwise the same test conditions. The increase in the melting rate with the increase in Stephan number also becomes more pronounced under the zero gravity condition.

Modeling evaluation on solid-liquid mixing characteristics in a dislocated guide impeller stirred tank

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Deyin Gu ◽  
Fenghui Zhao ◽  
Xingmin Wang ◽  
Zuohua Liu
Keyword(s):  
Power Consumption ◽  
Solid Particle ◽  
Particle Diameter ◽  
Solid Particles ◽  
Stirred Tank ◽  
Mixing Process ◽  
Solid Holdup ◽  
Aperture Ratio ◽  
Liquid Mixing ◽  
Solid Liquid

Abstract The solid-liquid mixing characteristics in a stirred tank with pitched blade impellers, dislocated impellers, and dislocated guide impellers were investigated through using CFD simulation. The effects of impeller speed, impeller type, aperture ratio, aperture length, solid particle diameter and initial solid holdup on the homogeneity degree in the solid-liquid mixing process were investigated. As expected, the solid particle suspension quality was increased with an increase in impeller speed. The dislocated impeller could reduce the accumulation of solid particles and improve the cloud height compared with pitched blade impeller under the same power consumption. The dislocated guide impeller could enhance the solid particles suspension quality on the basis of dislocated impeller, and the optimum aperture ratio and aperture length of dislocated guide impeller were 12.25% and 7 mm, respectively, in the solid-liquid mixing process. Smaller solid particle diameter and lower initial solid holdup led to higher homogeneity degree of solid-liquid mixing system. The dislocated guide impeller could increase solid particle integrated velocity and enhance turbulent intensity of solid-liquid two-phase compared with pitched blade impeller and dislocated impeller under the same power consumption.

scholarly journals Numerical Simulations and Experiments of Ignition of Solid Particles in a Laminar Burner: Effects of Slip Velocity and Particle Swelling

2020 ◽  
Author(s):  
Antonio Attili ◽  
Pooria Farmand ◽  
Christoph Schumann ◽  
Sima Farazi ◽  
Benjamin Böhm ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ignition Delay ◽  
Delay Time ◽  
Slip Velocity ◽  
Ignition Delay Time ◽  
Flame Structure ◽  
Particle Diameter ◽  
Point Particle ◽  
Solid Particles ◽  
Experimental Measurements

Abstract Ignition and combustion of pulverized solid fuel is investigated in a laminar burner. The two-dimensional OH radical field is measured in the experiments, providing information on the first onset of ignition and a detailed characterization of the flame structure for the single particle. In addition, particle velocity and diameter are tracked in time in the experiments. Simulations are carried out with a Lagrangian point-particle approach fully coupled with an Eulerian solver for the gas-phase, which includes detailed chemistry and transport. The numerical simulation results are compared with the experimental measurements in order to investigate the ignition characteristics. The effect of the slip velocity, i.e. the initial velocity difference between the gas-phase and the particle, is investigated numerically. For increasing slip velocity, the ignition delay time decreases. For large slip velocities, the decrease in ignition delay time is found to saturate to a value which is about 40% smaller than the ignition delay time at zero slip velocity. Performing a simulation neglecting the dependency of the Nusselt number on the slip velocity, it is found that this dependency does not play a role. On the contrary, it is found that the decrease of ignition delay time induced by the slip velocity is due to modifications of the temperature field around the particle. In particular, the low-temperature fluid related to the energy sink due to particle heating is transported away from the particle position when the slip velocity is non-zero; therefore, the particle is exposed to larger temperatures. Finally, the effect of particle swell is investigated using a model for the particle swelling based on the CPD framework. With this model, we observed negligible differences in ignition delay time compared to the case in which swelling is not included. This is related to the negligible swelling predicted by this model before ignition. However, this is inconsistent with the experimental measurements of particle diameter, showing a significant increase of diameter even before ignition. In further simulations, the measured swelling was directly prescribed, using an analytical fit at the given conditions. With this approach, it is found that the inclusion of swelling reduces the ignition delay time by about 20% for small particles while it is negligible for large particles.

An Investigation of the Effect of Nanoparticles on the Effectiveness of a Heat Exchanger

2007 ◽  
Author(s):  
V. Upender Rao ◽  
V. Sajith ◽  
T. Hanas ◽  
C. B. Sobhan
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Operating Temperature ◽  
Particle Surface ◽  
Weight Fraction ◽  
Copper Oxide Nanoparticles ◽  
Suspended Solid ◽  
Solid Particles ◽  
Particle Surface Area ◽  
Materials Used

Convective heat transfer can be improved by enhancing the thermal conductivity of the fluid. It has been established that fluids containing suspended solid particles of metallic origin in nanoscale dimensions, display enhanced thermal conductivity. Nanoparticle suspensions have superior qualities than suspensions of larger sized particles, such as more particle surface area, less possibilities of agglomeration and clogging and better stability. An experimental investigation on the effect of the inclusion of nanoparticles into the cooling fluid on the effectiveness of a heat exchanger is presented in this paper. An experimental double pipe heat exchanger with the hot fluid flowing through the inner tube was used in the study. Aluminum oxide and copper oxide nanoparticles with a size range of 20 to 30 nm suspended in water using ultrasonic agitation was used as the hot fluid, and water was used as the cold fluid passing through the annulus. The concentration of the suspended nanoparticles was varied to investigate its effect on the performance of the exchanger. The operating temperature is also used as a parameter in the study. Typically, an enhancement of 4.5 to 7 percent was observed in the effectiveness of the heat exchanger for 0.26% weight fraction of the nanoparticles in suspension, in an operating temperature range of 50–70°C. The effectiveness of the heat exchanger was found to increase with the concentration of nanoparticles for both materials used.

Exergy Analysis of a Solid-Oxide Fuel Cell, Gas Turbine, Steam Turbine Triple-Cycle Power Plant

2012 ◽  
Author(s):  
Rebecca Z. Pass ◽  
Chris F. Edwards
Keyword(s):  
Fuel Cell ◽  
Power Systems ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Combined Cycle ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Starting Point ◽  
Natural Gas Combined Cycle

In an effort to make higher efficiency power systems, several joint fuel cell / combustion-based cycles have been proposed and modeled. Mitsubishi Heavy Industries has recently built such a system with a solid-oxide fuel cell gas turbine plant, and is now working on a variant that includes a bottoming steam cycle. They report their double and triple cycles have LHV efficiencies greater than 52% and 70%, respectively. In order to provide insight into the thermodynamics behind such efficiencies, this study attempts to reverse engineer the Mitsubishi Heavy Industries system from publicly available data. The information learned provides the starting point for a computer model of the triple cycle. An exergy analysis is used to compare the triple cycle to its constituent sub-cycles, in particular the natural gas combined cycle. This analysis provides insights into the benefits of integrating the fuel cell and gas turbine architectures in a manner that improves the overall system performance to previously unseen efficiencies.

Parametric Studies of a Spectrally Selective, Two-Layered, Porous, Volumetric Solar Collector

1992 ◽  
Vol 114 (3) ◽  
pp. 150-156 ◽  
Author(s):  
D. A. Kaminski ◽  
S. Kar
Keyword(s):  
Solar Collector ◽  
Cone Angle ◽  
Particle Diameter ◽  
Solid Particles ◽  
Solar Flux ◽  
Radiative Properties ◽  
Critical Parameters ◽  
Fluid Temperature ◽  
Spectrally Selective ◽  
Parametric Studies

A porous, packed bed, volumetric solar collector consisting of two dissimilar layers of spherical beads is numerically modeled. The bed is irradiated on the top surface by concentrated solar flux isotropic within a known cone angle. A gas stream perfusing the bed is heated by convection with the solid particles. The equation of radiative transfer, which accounts for absorption, emission, and linearly anisotropic scattering in the bed, is simplified by employing the P1 differential approximation. The bed materials are spectrally selective in the solar and infrared wavelengths. Sensitivity studies are used to identify the critical input parameters of the system, and a baseline configuration, which incorporates the key requirements of an efficient solar collector, is adopted. Parametric studies are conducted on the mass flow rate, incident solar flux, top layer porosity, solar absorptivity, particle diameter, and degree of back scatter. Tailoring of the particle and fluid temperature profiles and enhancing the efficiency of the collector by an appropriate selection of these critical parameters is demonstrated. Various high-temperature ceramics with suitable radiative properties are identified and their relative performance in the collector is assessed.

Dual Brayton Cycle Gas Turbine Pressurized Fluidized Bed Combustion Power Plant Concept

1997 ◽  
Author(s):  
Xing L. Yan ◽  
Lawrence M. Lidsky
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Power Plants ◽  
Environmental Benefits ◽  
Brayton Cycle ◽  
Plant Design ◽  
Fluidized Bed Combustion ◽  
Electric Power Plants ◽  
Wide Range ◽  
Pressurized Fluidized Bed Combustion

High generating efficiency has compelling economic and environmental benefits for electric power plants. There are particular incentives to develop more efficient and cleaner coal-fired power plants, to permit use of the world’s most abundant and secure energy source. This paper presents a newly-conceived power plant design, the Dual Brayton Cycle Gas Turbine PFBC, that yields 45% net generating efficiency and fires on a wide range of fuels with minimum pollution, of which coal is a particularly intriguing target for its first application. The DBC-GT design allows power plants based on the state-of-the-art PFBC technology to achieve substantially higher generating efficiencies while simultaneously providing modern gas turbine and related heat exchanger technologies access to the large coal power generation market.

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